The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 11-2152273 filed Jul. 29, 1999.
1. Field of the Invention
The present invention relates to stage apparatus for positioning a sample with high precision within a two-dimensional plane, and an inspection apparatus having the stage apparatus.
2. Description of the Related Art
Conventional stage apparatus are used with exposure apparatus for manufacturing semiconductor devices etc. using lithographic processes, inspection apparatus for inspecting circuit patterns formed on the semiconductor devices, and with ultraprecise manufacturing apparatus, and are used to position samples such as wafers, etc. within a two-dimensional plane in a highly-precise manner.
For example, as shown in FIG. 21, a magnetic levitation-type stage apparatus 200 disclosed in Japanese Patent Laid-open Publication No. Hei. 9-17846 comprises a rectangular fixed stage 211 and a rectangular moving stage 212 smaller than the fixed stage 211 and the sample is mounted on the moving stage 212. The fixed stage 211 comprises a multiplicity of magnets 213 arranged in longitudinal and lateral direction, and a sealed tank 214 for housing the magnets 213. An upper plate of the sealed tank 214 is made of a material with a low permeability. Six permanent magnets 215 and three gap sensors 216 are fitted to the bottom surface of the moving stage 212 levitated above the fixed stage 211. The three gap sensors 216 measure the position of the moving stage 212 in a direction Z and inclination in directions xcex1 and xcex2, taking the upper plate of the sealed tank 214 as a reference.
Three laser interferometers 217 are provided about the periphery of the fixed stage 211. The three laser interferometers 217 measure the position of the moving stage 212 in directions X and Y, and inclination in a direction xcex8.
The magnets 213 and the permanent magnets 215 constitute a planar motor. Attractive force, repulsion, and Lorentz""s force are generated by supplying current to the magnets 213 of the planar motor so that the moving stage 212 can be driven.
At the stage apparatus 200, control apparatus (not shown) receiving information from the gap sensors 216 and the laser interferometers 217 controls the current of the magnets 213 so as to drive the moving stage 212 to the desired position and posture. The position of samples such as wafers etc. mounted on the moving stage 212 can therefore be decided with six degrees of freedom in the direction X, Y, Z, xcex8, xcex1 and xcex2.
Degassification from the magnets 213 is prevented because the magnets 213 are housed within the sealed tank 214 and the stage apparatus 200 can therefore be employed not just in the atmosphere, but can also operate in clean rooms and in a vacuum.
On the other hand, as shown in FIG. 22, with a stage apparatus 300 disclosed in Japanese Patent Laid-open Publication No. Hei. 3-73513, slide sections 301x and 301y are moved along guide rails 302x and 302y by drive screws 303x and 303y, with the guide rail 302y being fixed to the slide section 301x. 
At the slide sections 301x and 301y, supply pipes 304x and 304y for supplying high-pressure gas (dry air) are connected to a gap between the slide sections 301x and 301y and the guide rails 302x and 302y. 
Gas exhaust sections 309x and 309y are fitted to the slide sections 301x and 301y and are connected to exhaust pipes 310x and 310y linked to a vacuum pump (not shown).
At the stage apparatus 300, high-pressure gas supplied from the supply pipes 304x and 304y to the gap between the slide sections 301x and 301y and the guide rails 302x and 302y then flows in the direction of a gap between the gas exhaust sections 309x and 309y and the guide rails 302x and 302y and is discharged rapidly to outside of the vacuum chamber via the exhaust pipes 310x and 310y. 
The slide sections 301x and 301y (and the gas exhaust sections 309x and 309y) therefore move in directions X and Y while being levitated from the guide rails 302x and 302y. A sample 313 is mounted at a table 308 on the slide section 301y. 
With the stage apparatus 300 where bearings for X and Y-directions are static pressure gas bearing slides, high pressure gas for levitating the slide sections 301x and 301y (gas exhaust sections 309x and 309y) from the guide rails 302x and 302y is released to the outside of the vacuum chamber and use in a vacuum or special gas is possible.
However, with the magnetic levitation-type stage apparatus 200 (FIG. 21) described above, all positions and postures of the moving stage 212 have to be simultaneously controlled by the planar motor constituted by the magnets 213 and the permanent magnets 215 (control of six axes) and it is necessary to drive the multiplicity of magnets 213 independently, which requires an extremely complex control system.
Cables (not shown) etc. fitted to the moving stage 212 are influence by pulling force and vibrations (disturbances) and it is therefore difficult to exert control in such a manner that inter-axial interference does not occur, even with a complex control system. This puts a limit on the extent to which positioning precision can be improved with the related stage apparatus 200.
With the stage apparatus 300 (FIG. 22) provided with the static pressure gas bearings, the exhaust pipes 310x and 310y are constituted by metal bellows-like members which ensure that the exhaust pipes 310x and 310y while at the same time ensuring that the exhaust pipes 310x and 310y extend and contract. However, it is difficult to smoothly extend and contract according to movement of the slide sections 301x and 301y. 
There are therefore cases where unnecessary reactive force is applied to the slide sections 301x and 301y from the metal bellows-like members when the slide sections 301x and 301y move and this places limitations on the extent to which positioning precision can be improved.
It is therefore the object of the present invention to provide a stage apparatus where even if a control system for a planar motor constituting a drive source is simplified, inter-axial interference is suppressed and highly precise positioning is possible.
It is a further object of the present invention to provide inspection apparatus capable of improving the precision of positioning a sample mounted on a table.
It is a still further object of the present invention to provide beam irradiation apparatus capable of improving the precision of positioning a sample mounted on a table.
The stage apparatus of the present invention comprises a base member, a table member provided at the base member and moving within a plane parallel to a guide plane, a first guide member for guiding the table member in a first direction and moving along the guide plane, a second guide member for guiding the first guide member in a second direction perpendicular with respect to the first direction, a non-contact bearing for providing guidance and support in such a manner that there is no contact between the base member, table member and second guide member, and the first guide member, a planar motor constituted by magnets provided at one of either the base member or the table member and electromagnets provided at the remaining one of either the base member or the table member, and movement control apparatus for controlling the planar motor, generating drive force in directions parallel to the guide plane, and moving the table member.
In this stage apparatus, the first guide member is provided with an opening penetrating to the guide plane so that the table member moves along the guide plane within the opening and is provided with levitation apparatus for causing the table member to levitate away from the guide plane within the opening.
The stage apparatus comprises a first urging device for urging the table member towards the guide plane, and a second urging device for urging the first guide member towards the guide plane. The first urging device comprises a first urging member provided integrally with the first guide member. It is advantageous to provide a non-contact bearing which provides guidance and support in a non-contact manner between the first urging member and the table member. The second urging device comprises a second urging member provided integrally with the second guide member. It is advantageous to provide a non-contact bearing which provides guidance and support in a non-contact manner between the second urging member and the first guide member.
With this stage apparatus, it is advantageous to provide the second guide member integrally with the base member. The levitation apparatus is constituted of a levitation control apparatus for controlling the planar motor so as to generate drive force in directions parallel to the normal of the guide plane.
The levitation apparatus can also be a static pressure bearing which provides guidance and support in a non-contact manner between the table member and the guide plane using fluid. The non-contact bearing can also be a static pressure bearing which provides guidance and support via a fluid. The static pressure bearing can be a static pressure gas bearing employing gas as a fluid. The static pressure bearing can comprise pads for expelling fluid and a discharge unit provided about the pads for discharging fluid expelled from the pads.
An inspection apparatus of the present invention comprises the aforementioned stage apparatus, a irradiation device for irradiating a sample mounted at the stage apparatus with a beam and detection means for detecting a secondary beam generated from the sample as a result of being irradiated with the beam.
The stage apparatus can also further comprise a guide member driver for generating drive force with respect to the first guide member in directions parallel to the guide plane. The guide member driver can be provided at the base member adjacent to the planar motor and can be embedded in the base member.
The guide member driver can be located along the direction of movement of the first guide member and the first guide member of the stage apparatus can be fitted into the table member.
The beam irradiation apparatus of the present invention is equipped with a irradiation unit for irradiating a sample mounted at the stage apparatus with a beam. A mask having a pattern to be transferred to the sample is located between the irradiation unit and the sample and the pattern of the mask is projected onto the sample using the beam official irrdiates form the irradiation unit in accordance with movement of the stage apparatus. The stage apparatus can therefore be located within a vacuum with this beam irradiation apparatus.